Remedies & causes: you are invading his private territory&he may not like that. Move slowly. If he tries to bite just make a fist & let his bill slide off the tightened skin on the back of your hand-he cannot get a grip on you. Watch his eyes-you can distract him if he is looking at you. Birds like dominance-don't stand over him to dominate that position that he wants. Talk in a quiet even tone to reassure him. Sometimes offering a treat will entice actions or using it as a reward. These guys are smart-they see everything you do. They can sense if you are frightened. Abuse at another can cause frustration for you. Molting can cause anguish. In captivity they live 20-80 years or longer. Never hit your bird(physical & mental) abuse. It takes time, patience and love. After some time let your bird have free time out of the cage. If your birds' eyes dilate when you speak to him he is listening to you & probably will be a talker. If he ignores you, chances he is letting you know he could care less. See: http://www.birdtricks.com/parrot-biting.html or http://birds.about.com/od/behaviorandtraining/a/aggressivebirds.htm
You can get a bird to stop biting you when you go near it by making sure you don't have a loud reaction when it bites you since they get excited or take pleasure when you yell. Also when your bird is biting you need to reprimand it gently.